Candido de esteve llatas



UNITED STATES PATENT OE IcE.

CANDIDO DE ESTEVE LLATAS, OF PARIS, FRANCE.

PROCESS OF MANUFACTURING STEEL.

SPECIFICATION forming part of Letters Patent No. 595,319, dated December 14, 1897.

Application filed May 27, 1897. Serial No. 638,426. (No specimens.)

To all whom, it may concern.-

Be it known that I, CANDIDO DE EsTEvE LLA'IAS, a citizen of the French Republic, residing at 38 Avenue de la Republique, Paris, in the French Republic, have invented new and useful Improvements in the Manufacture of Steel, (in respect whereof I have applied for, but not yet obtained, Letters Patent in Great Britain to bear date December 16, 1896, No. 28,880,) of which the following is a specification.

This invention relates to the manufacture of steel, and has for its object the production of steel of the highest qualities, (equal, for example, to that commonly known as crucible steel,) the product possessing remarkable uniformity and the cost of manufacture being but little in excess of that of Bessemer, Siemens-Martin, or other steel of like class.

As the result of numerous experiments I have found that in the production of steel possessing the various qualities or characteristics suited to the different purposes to which this metal is applied it is necessary that carbon, manganese, and silicon should be pres ent in certain definite proportions, and, further, that a regular gradation prevails between these elements, the proportions of carbon and silicon being on the ascending scale, as between mild and hard steel, while the proportion of manganese is on the descending scale.

It is well known that an augmentation in the proportion of carbon has the effect of increasing the hardness of steel; but in manufacturing steel of different grades according to my improved method not only is the proportion of the carbon varied, but the proportions of the manganese and silicon are also regulated according to a definite scale. The scale is substantially as follows:

Quality or Carbon. Manganese, Silicon,

From this table it will be seen that with each increase of 0.050 per cent. of carbon there is a decrease of 0.025 per cent. of manganese and an increase of 0.025 per cent. of silicon and that no single element is ever varied without both other elements being also varied in a definite ratio. Thus supposing a somewhat harder or a somewhat softer quality of steel is desired instead of ascertaining or endeavoring to ascertain by repeated trial and failure in what direction and in what degree the carbon, manganese, and silicon should be respectively varied a user is, byvirtue of my discovery and with the aid of my table, onabled to determine with certainty the precise manner in which these elements should be varied in order to insure a good result.

In carrying my improved process into effect I melt the charge in a Bessemer or other converter or in a Sien'iens-Martin or other suitable furnace and proceed until the charge is brought to the desired point of purity as regards the proportion of carbon present, according to the particular quality of mild, medium, or hard steel required. If the proportion of carbon be lower or higher than that specified in the column selected, I carburize or decarburize the charge until the proper proportion is reached. In carburizing carbureted iron of any suitable kind may be introduced into the charge. XVhcn the charge presents or by carburaiion or decarburation has assumed the desired condition as regards the proportion of carbon present, the necessary quantities of manganese and of silicon are added, so as to produce a metal which on tapping presents the proportions indicated in the particular line or column of the table for the time being in use. The manganese and silicon before being introduced are heated to a cherry-red. When operating with the aid of a Bessemer or other converter, these materials may be introduced simultaneously, butwhen a Siemens-Martin or similar furnace is employed the manganese is first introduced, and when this has been absorbed the silicon is added. The latter having been absorbed the tapping takes place.

What I claim as my invention, and desire to secure by Letters Patent, is

In the manufacture of cast-steel of various grades from that containing 0.150 per cent. of carbon, 0.625 per cent. of manganese and 0.025 per cent. of silicon for mild steel to that containing 1.000 per cent. of carbon, 0.200 per cent. of manganese and 0.450 per cent. of silicon for hard steel, the herein-described method of treating the charge, which consists in varying the proportions of carbon, manganese and silicon in the definite ratios set forth according to the grade of steel required; the proportion of the manganese being diminished 0.025 per cent. and that of the silicon being increased 0.025 per cent. for each increase of 0.050 per cent. in the proportion of the carbon.

CANDIDO DE ES'llCVE LLATAS.

Witnesses:

Janus DAVISON, Sur'rn. Fiscnnn. 

